Diesel vs gas......................

rhagfo wrote:
This is from "Ram Hemi owners - What octane do you use?"

GOrsted wrote:

Dougie123 wrote:
Since we are on the subject, what kind of mpg do you all average while towing?

I'm hitting 10mpg towing my #6500 HTT.

OhhWell wrote:
87 around town, 89 or higher mix when towing. Alot of the time there is quite a bit of 87 in the tank so I will top off with 93 before leaving on a trip.

I would love to see if someone has done the hand calculations to find if there is a noticeable increase in MPG by running 89 octane.

For the person asking about MPG, I get about 7.5 to 9 depending on wind etc with the camper in my Sig. I did have one miracle trip coming back from coco beach with what must have been a tail wind the whole way where I just broke 10 mpg.

With my previous '93 Sunline low slung 6,000GVWR trailer I used to break 10 every now and then but that thing sat so low it was about even with my truck topper.

I know I have the largest truck equiped with a Hemi but I would be very suspect of anyone that claims consistant towing MPG in the double digits with a full size TT.

I average 8.5 MPG towing our 30' fifth wheel.

The 5.7L Hemi in my Power Wagon recommends 89 octane for normal driving and premium (high-octane) while towing:

"When pulling a heavy load or driving a fully loaded vehicle when the humidity is low or the temperature is high, use a premium (high-octane) unleaded fuel to help prevent spark knock."

Living in AZ, I tow in low humidity AND high temperatures. When I first purchased my Power Wagon I followed this and used 91 octane while towing until someone on another forum said it was not necessary and I was wasting money, so I tried towing with mid-grade 89. Well, the difference was quite noticeable. I had always been able to tow our fifth wheel on 260 on the grade to the top of the Mogollon Rim in 2nd gear. With mid-grade I was down into 1st gear with about a mile to go to reach the top. Back to premium for towing and the next trip (and subsequent ones) I was once again able to keep it in 2nd gear and maintain a higher speed to the top. This last spring the temperatures were a little cooler and with the price of fuel I again tried mid-grade and again I was down into 1st gear with about a mile to go to reach the top.

I didn't notice much difference in MPG, but there was a definite improvement in performance. I will be towing with premium fuel from now on.

Wow! Now I know why I changed from a gasser to Diesel!

Premium fuel to tow and only getting 7.5 to 9 mpg. I can't make a statement on the grade on 260 never been there, but 1st and second gear??

My Cummins is a daily driver 12 mpg towing (12K 5er), 14 city, and 20 mpg @ 65 on the open road.

Lately I did a short pull to Sanibel using only 87 octane because I had crank slap and actually wanted as little power as possible while we squeezed as many miles out of the current engine saving for a rebuild.

The largest incline I had to worry about was the 1st Sanibel Causeway bridge which is aout a 6.5% or 6.6 feet every 100 feet to be exact-ish grade for a whole whopping quarter mile up. BUT, even with engine issues and 87 octane, it roared up it just fine. You don't need high octane to pull but from the account pulling up 260 (I'm not familiar with that either), it sure seems to help. It may be an altitude and humidity thing like the poster said. Forced induction may help with that too heheh.

Around 8 or 9 is the norm for a gasser. That is well known. It's also well known that turbo diesels get better gas milage. None of this should shock anyone really.

What I would really like to see is a comarison of towing with an ecoboost on 87 and 93 octane.